Method for transmitting at least one group message, associated radio communication network, subsystem and mobile communication device

ABSTRACT

In order to transmit at least one group message to at least one group consisting of one or more subscriber devices of a radio communications network, the respectively assigned, higher order radio network control unit specifically controls whether and/or how many subscriber devices per radio cell are currently registered with the respective group.

BACKGROUND OF THE INVENTION

WO 98/35422 discloses a method and device, wherein group messages aretransmitted in a packet-oriented radio network having at least onesupport node, a number of group users, and at least one defined area.

U.S. Pat. No. 5,640,443 discloses a mobile telephone system whichperforms telephone communication with a group consisting of mobilesubscribers in order to improve the rate of completion of incoming callsand communication quality, wherein the group of mobile subscribers eachsend information including location number and subscriber number.

The present invention is directed toward a method of transmitting atleast one group message as effectively as possible to one or moresubscriber devices of at least one group in a radio communicationnetwork. The present invention is further directed toward an associatedradio communication network, subsystem and mobile communication device.

SUMMARY OF THE INVENTION

Specifically, the present invention provides for a method fortransmitting at least one group message to at least one group of one ormore subscriber devices and at least one radio cell of the radiocommunication network, the base station of each radio cell beingcontrolled by at least one higher-order radio network controller,wherein the higher-order radio network controller monitors how manysubscriber devices in each radio cell are currently subscribed to therespective group, wherein at least one information signal indicating tothe higher-order radio network controller whether a respectivesubscriber device is currently subscribed to the respective group istransmitted by the respective subscriber device via an air interface ofthe base station of its present location radio cell to the higher-orderradio network controller, with the respective user ID not being added tothe information signal, and wherein at least one further informationsignal indicating to the higher-order radio network controller whetherthe respective subscriber device can be unsubscribed from the respectivegroup, is leaving its present location radio cell and/or is switchingoff, is transmitted by the respective subscriber device via the airinterface of the base station of its present location radio cell to thehigher-order radio network controller, with the user ID again not beingadded to the further information signal.

The present invention also provides for, in connection with theabove-described method, an associated radio communication network,associated subsystem of the radio communication network and anassociated mobile communication device.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 schematically illustrates networks elements and theirinterconnection in the UTRAN subsystem of UMTS (Universal MobileTelecommunication System).

FIGS. 2, 3 each schematically illustrate an MBMS context in the UTRANsubsystem of FIG. 1 which is administered according to the inventivemethod by at least one higher-order radio network controller of thesubsystem.

FIGS. 4 through 6 each schematically illustrate the signaling on the airinterface between the relevant subscriber device and the higher-orderradio network controller in the UTRAN subsystem of UMTS according toFIG. 1 for implementing the method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Elements with identical function and mode of operation are denoted bythe same reference characters in FIGS. 1 through 6.

In many services and applications provided in modern mobilecommunication systems, messages are to be transmitted not to a single,but to two or more mobile communication subscribers of at least onepredefined group. Examples of such services and applications arenewsgroups, videoconferencing, video-on-demand, distributedapplications, etc.

For transmitting the messages to the various subscribers it is possibleto send a copy of the data to each recipient separately. Although thistechnique is easy to implement, it is unsuitable for large groups. Asthe same message is transmitted via N (N=number of message recipients)individual connections (unicast connections) and is multiply sent viacommon connection paths, this method requires a very high bandwidth.

A better option is provided by so-called multicast transmission. In thiscase, the various subscribers to which the same message is to betransmitted are combined to form a group (multicast group), with thisgroup being assigned an address (multicast address). The data to betransmitted is then sent to this multicast address only once. Ideally,the multicast (=MC) message is sent only once via common transmissionpaths from the sender to the recipients. It is not necessary for thesender to know where and how many recipients are concealed behind therelevant multicast address. In order to be able to receive messages of aparticular multicast group, a subscriber must be subscribed to themulticast group.

With broadcast, communications are sent to a group of subscribers withina geographical area. The area to which the broadcast messages are sentout is known as the broadcast area. The size of the broadcast area isdetermined by the network operator, the message ideally beingtransmitted only once via common connection paths, as in the case ofmulticast. The disadvantage of this method, however, is that all thesubscribers within the broadcast area are able to read broadcastmessages, even if they are not authorized. In order to read particularmessages only and discard or filter others, subscribers can makeappropriate settings on their terminals. Explicit subscription to abroadcast service is not required.

The so-called Multimedia Broadcast and Multicast Service (MBMS) isdescribed in the specifications of the third generation of mobile radiosystems, particularly for UMTS (Universal Mobile TelecommunicationSystem). MBMS enables multimedia data to be transmitted via multicastand via broadcast.

Only the network elements of the UMTS access network, the so-called UMTSTerrestrial Radio Access Network (UTRAN), as a subsystem of the UMTSnetwork will be considered in further detail below. By way of example,FIG. 1 schematically illustrates the following components of the networkelements and their interconnection:

NodeB:

A NodeB (base station), here, the two base stations NodeB1, NodeB2, is anetwork component serving one or more radio cells via at least one airinterface. The relevant NodeB is used for communication via at least oneair interface between the fixed network part or higher-order mobilenetwork part of the UMTS and the subscriber devices, particularly mobileradio devices, which are located in the radio cell around the basestation.

Radio Network Controller (Abbreviation: RNC):

An RNC controls the resources of the air interface and supplies andcontrols one or more base stations (NodeBs).

Subscriber Device (UE):

The UE is, in particular, a mobile terminal which is connected to theUTRAN via the air interface.

In FIG. 1, for example, the two base stations NodeB 1, NodeB2 and theirassociated radio cells CE1, CE2 are controlled by the higher-order radionetwork controller RNC1, the base station NodeB1 and the base stationNodeB2 being connected to the jointly assigned radio network controllerRNC1 via the fixed lines LI1 and LI2, respectively. The radio cell CE1of the base station NodeB1 contains the three subscriber devices UE1,UE2, UE3 which are subscribed and logged onto the group GR1, andcommunicate with the base station NodeB1 via the air interface LS1 andthe controller RNC1 connected thereto.

The MBMS specifications lay down that the data of an MBMS service onlyshall be sent out in the radio cells in which the subscriber devices orUEs wishing to receive such service are also located. In order to beable to implement this, the UTRAN, in particular the RNC, requiresknowledge or information as to whether subscribers or UEs wishing toreceive a particular MBMS service are located in one of the radio cellsfor which the RNC is responsible. According to the prior art, the UTRAN,in particular the RNC, does not have this information. It is, inaddition, established that a subscriber device (=UE) also shall be ableto receive MBMS in so-called “idle mode.” In this state (idle mode), theUTRAN has no knowledge concerning the UE; i.e., it does not even knowthat it is in one of its radio cells at all.

According to the prior art, the UTRAN is therefore unable to make adecision as to whether MBMS data shall be transmitted in radio cells,even if UEs wishing to receive the service are located there.

For this exemplary embodiment, a radio cell (cell ID=N; cell ID=cellidentity) such as CE1 will be considered which is supplied by a NodeB(e.g., NodeB1, and an RNC, e.g., RNC1). In addition, an MBMS service(MBMS group ID=XYZ) will be considered.

Firstly, it will be shown, on the basis of two examples, how an MBMScontext can be implemented and introduced advantageously in the UTRAN;in particular, in the RNC.

EXAMPLE 1

In the radio cell CE1 with cell ID “N=1” there is 1 (one) subscriberwith UE ID “A” (this information element is optional) wishing to receivethe MBMS service having MBMS service ID “XYZ.” This MBMS context isillustrated, by way of example, in FIG. 2.

EXAMPLE 2

Let it be assumed that in the radio cell CE1 with cell ID “N=1” thereare now 3 UEs UE1, UE2, UE3 having UE IDs “A”, “B” and “C” (thisinformation element is optional) wishing to receive the MBMS servicehaving MBMS service ID “XYZ.” This MBMS context is illustrated by way ofexample in FIG. 3.

When there are no subscribers wishing to receive the MBMS service inquestion in the radio cell CE1 in question, no MBMS context isadministered or maintained in the RNC for the MBMS service in the radiocell.

Secondly, there now will be shown the form taken by advantageoussignaling between UE and RNC, on the basis of which the MBMS context isestablished, adapted and/or removed in the RNC.

It will be assumed that there is still no UE wishing to receive the MBMSservice “XYZ” in the radio cell in question; e.g., CE1. No MBMS contextis therefore maintained in the RNC for the MBMS service and the radiocell, it being further assumed that a UE such as UE1 with UE ID “A”changes over to the radio cell CE1 in question with cell ID “N=1” and isalready subscribed to the MBMS service in question with MBMS service ID“XYZ.” On the basis of measurements, the UE=UE1 now detects that it isin a new cell. According to the present invention, the subscriber deviceUE1 now sends an information signal IS1 (“MBMS notification”) to thehigher-order radio network controller (=RNC) RNC1. This MBMSnotification contains the MBMS group ID to which the subscriber deviceUE1 is subscribed (e.g., the TMGI (=“temporary mobile group identifier”)and optionally information about its identity (UE ID).

The RNC, here RNC1, now establishes the MBMS context according to thepresent invention. In this case, this is comparable to the aboveExample 1. The same “MBMS notification” IS1 is also sent by thesubscriber device (=UE) to the RNC if the UE is already in the radiocell in question and re-subscribes to the MBMS service in question;i.e., registers and is therefore “on line” (or actively connected). Thissignaling scenario is shown in FIG. 4.

The information signal IS1 (“MBMS notification”) is now transmitted tothe higher-order radio network controller, in this case RNC1, by each UEwhich changes over to the radio cell in question and is subscribed tothe MBMS service in question, and for each UE that is already in theradio cell in question and subscribes to the MBMS service in question.The MBMS context in the RNC for this radio cell and this MBMS service isthen adapted accordingly.

If required, notification or information elements of this kind, such asMBMS group ID and UE-ID also may be incorporated in messages alreadypresent according the prior art and sent to the relevant RNC.

If a UE leaves the radio cell in question, it suitably re-transmits inthe new radio cell an MBMS notification (e.g., IS1), to the RNCresponsible (e.g., RNC1), which then administers or maintains acorresponding MBMS context for the new radio cell and the MBMS service.In addition to or independently from this, this radio-cell-changing UEsuitably transmits in the old radio cell (i.e., in the radio cell whichthe UE is just leaving), another information signal (e.g., IS2 (“MBMSleave”), that is a notification or message, to the relevant RNC so thatthe latter knows that one less UE wishing to receive the MBMS service inquestion is now in the radio cell in question. The “MBMS leave message”usefully contains the information elements MBMS group ID (e.g., theTMGI) and optionally the UE-ID of the subscriber device (=UE) sendingthe “MBMS leave message.” The RNC then usefully adapts the MBMS contextfor that radio cell and that MBMS service accordingly. This signalingscenario is shown in FIG. 5 where the information or notification signalof the “MBMS leave message” transmitted by the subscriber device UE1 tothe relevant higher-order radio network controller RNC1 on leaving theradio cell CE1 is denoted by IS2.

This “MBMS leave message” IS2 also is usefully transmitted if the UEremains in the radio cell in question and unsubscribes from the MBMSservice. This signaling scenario is shown in FIG. 6.

If required, the information elements such as MBMS group ID and UE-IDalso may be incorporated in messages already provided according theprior art and sent to the RNC.

If the last UE wishing to receive data on the relevant MBMS service hasleft the radio cell in question or has unsubscribed from the relevantMBMS service and sent a corresponding “MBMS leave message” to the RNC,the latter clears down or deletes the MBMS context for that radio celland that MBMS service.

In general terms, an MBMS context is preferably introduced in the UTRANwhich describes for each radio cell whether or how many subscribers havesubscribed to an MBMS group (e.g., described by an MBMS group identity).The MBMS context is maintained, administered and modified in the UTRAN;in particular, the RNC. The MBMS context enables the UTRAN to knowwhether and how many UEs subscribed to a particular MBMS service are inthe radio cells administered by it. On the basis of this information,the UTRAN subsystem, in particular the RNC, can decide whether or notMBMS data will be sent to a radio cell. Moreover, the UTRAN can, ifnecessary, decide on the basis of the MBMS context, in the case of asmall number of subscribers, whether point-to-point transmission (eachsubscriber receives his/her data via connections assigned to him/her) orpoint-to-multipoint transmission (the subscribers receive their data viaa common connection) is to be carried out.

Optionally, the MBMS context in the UTRAN additionally containsinformation as to which UEs (in particular, which UE identities) are inan MBMS group. This information can be used, for example, if the UTRANdecides in the case of a small number of recipients to usepoint-to-point transmission for transmitting MBMS data. The UEidentities are then used for setting up the subscriber-specificpoint-to-point connections.

The MBMS-service-specific and radio-cell-specific MBMS context ispreferably established in the relevant higher-order radio networkcontroller responsible as soon as the first UE in the radio cell wishesto receive an MBMS service. There the MBMS context is modified oradapted in the controller as soon as new subscriber devices (UEs)wishing to receive the same MBMS service are in the radio cell or if UEsleave the radio cell or no longer wish to receive the service. The MBMScontext is usefully cleared down as soon as there is no longer a UEwishing to receive the specific MBMS service in the radio cell.

As soon as a new UE is in a radio cell, it sends a notification(hereinafter, referred to as an “MBMS notification”), to the UTRAN, inparticular to the RNC. This MBMS notification preferably contains atleast the MBMS group identity (e.g., the TMGI (Temporary Mobile GroupIdentity)) or a number of identities (if UE is subscribed to a number ofMBMS services) uniquely identifying an MBMS service. Optionally, the“MBMS notification” additionally may contain the UE identity of the UEthat has sent the message.

The relevant UE sends the “MBMS notification” to the higher-order radionetwork controller (RNC) responsible, particularly if it:

-   -   is in a radio cell and subscribes to a new MBMS service, and/or    -   moves from one radio cell to a new radio cell, the UE detecting        for example, on the basis of messages that it is in a new radio        cell and automatically sending an MBMS notification to the        UTRAN.

In order for the UTRAN to adapt to the MBMS context if UEs leave theradio cell, turn off, and/or unsubscribe from the MBMS service inquestion, the relevant UE in these cases usefully sends a message to theUTRAN so that the UTRAN knows that there is now one less UE in thatradio cell. When the “old” radio cell is left, a message is thereforesent in the “old” cell to the “old” base station with its assignedcontroller to inform it that there is now one less UE present, and amessage is sent in the “new” cell to the “new” base station with itsassigned controller to inform it of the presence of one more UE wishingto receive a particular MBMS service. Within the scope of the presentinvention, this message is designated “MBMS leave message.” This “MBMSleave message” preferably contains the MBMS group identity (e.g., theTMGI (Temporary Mobile Group Identity)) or if required a number ofidentities (if the relevant UE is subscribed to a number of MBMSservices) which uniquely identify an MBMS service. Optionally, the “MBMSleave message” additionally may contain the UE identity of the UE thathas sent the message.

Within the scope of the present invention, the following abbreviationsand terms have been employed which have been introduced as standard orare widely used particularly in mobile communications as acronyms and insome cases definitions:

ID Identity (e.g. UE ID uniquely describes a UE) MBMS MultimediaBroadcast/Multicast Service NodeB Base station in the UMTS RNC Radionetwork controller TMGI Temporary Mobile Group ID (uniquely identifiesthe MBMS group) UE Subscriber device (mobile radio device in the UMTSnetwork) UMTS Universal Mobile Telecommunication System UTRAN UMTSTerrestrial Radio Access Network

In this way, there is provided a subsystem for a radio communicationnetwork for transmitting at least one group message to at least onereceiving subscriber device. This subsystem of the radio communicationnetwork is formed by at least one subscriber device and at least onehigher-order radio network controller which are implemented to carry outthe method according to the present invention.

Although the present invention has been described with reference tospecific embodiments, those of skill in the art will recognize thechanges may be made thereto without departing from the spirit and scopeof the present invention as set forth in the hereafter appended claims.

1. A method for transmitting at least one group message to at least onegroup of one or more subscriber devices in at least one radio cell of aradio communication network, a base station of each radio cell beingcontrolled by at least one higher-order radio network controller, themethod comprising: monitoring, via at least one higher-order radionetwork controller, how many subscriber devices in each radio cell arecurrently subscribed to the respective group; and transmitting to the atleast one higher-order radio network controller, by a respectivesubscriber device via an air interface of the base station associatedwith a current location radio cell of the respective subscriber device,at least one information signal indicating to the at least onehigher-order radio network controller whether the respective subscriberdevice is currently subscribed to the respective group, with a user IDof the respective subscriber device not being added to the at least oneinformation signal.
 2. A method for transmitting at least one groupmessage to at least one group of one or more subscriber devices asclaimed in claim 1, wherein the method further comprises transmitting tothe at least one higher-order radio network controller, by therespective subscriber device via the air interface of the base stationassociated with the current location radio cell, at least one furtherinformation signal indicating to the at least one higher-order radionetwork controller whether the respective subscriber device at least oneof can be unsubscribed from the respective group, is leaving the currentlocation radio cell and is switching off, with the user ID of therespective subscriber device not being added to the at least one furtherinformation signal.
 3. A method for transmitting at least one groupmessage to at least one group of one or more subscriber devices asclaimed in claim 1, wherein the user ID of the respective subscriberdevice is added to the at least one information signal and the at leastone further information signal.
 4. A method for transmitting at leastone group message to at least one group of one or more subscriberdevices as claimed in claim 1, wherein the at least one informationsignal and the at least one further information signal are generated bya UMTS for a multicast transmission.
 5. A method for transmitting atleast one group message to at least one group of one or more subscriberdevices as claimed in claim 1, wherein the respective subscriber deviceis a mobile communication device.
 6. A radio communication network fortransmitting at least one group message to at least one group of one ormore subscriber devices in at least one radio cell of the radiocommunication network, comprising: one or more subscriber devices; arespective base station for each radio cell in the radio communicationnetwork; and at least one higher-order radio network controller forcontrolling the base stations; wherein the at least one higher-orderradio network controller monitors how many subscriber devices in eachradio cell are currently subscribed to a respective group, and whereinat least one information signal indicating to at least one higher-orderradio network controller whether a respective subscriber device iscurrently subscribed to the respective group is transmitted by therespective subscriber device via an air interface of the base stationassociated with a current location radio cell of the respectivesubscriber device to the at least one higher-order radio networkcontroller, with a user ID of the respective subscriber device not beingadded to the at least the one information signal.
 7. A radiocommunication network as claimed in claim 6, wherein at least onefurther information signal indicating to the at least one higher-orderradio network controller whether the respective subscriber device atleast one of can be unsubscribed from the respective group, is leavingthe current location radio cell of the respective subscriber device, andis switching off, is transmitted by the respective subscriber device viathe air interface of the base station of the current location radio cellof the respective subscriber device to the at least one higher-orderradio network controller, with the user ID of the respective subscriberdevice not being added to the at least one further information signal.8. A subsystem of a radio communication network for transmitting atleast one group message to at least one group of one or more subscriberdevices in at least one radio cell of the radio communication network,the radio communication network including a respective base station foreach radio cell of the radio communication network, comprising: one ormore subscriber devices; and at least one higher-order radio networkcontroller for controlling the base stations; wherein the at least onehigher-order radio network controller monitors how many subscriberdevices in each radio cell are currently subscribed to a respectivegroup, and wherein at least one information signal indicating to the atleast one higher-order radio network controller whether a respectivesubscriber device is currently subscribed to the respective group istransmitted by the respective subscriber device via an air interface ofthe base station associated with a current location radio cell of therespective subscriber device to the at least one higher-order radionetwork controller, with a user ID of the respective subscriber devicenot being added to the at least one information signal.
 9. A subsystemof a radio communication network as claimed in claim 8, wherein at leastone further information signal indicating to the at least onehigher-order radio network controller whether the respective subscriberdevice at least one of can be unsubscribed from the respective group, isleaving the current location radio cell of the respective subscriberdevice, and is switching off, is transmitted by the respectivesubscriber device via the air interface of the base station of thecurrent location radio cell of the respective subscriber device to theat least one higher-order radio network controller, with the user ID ofthe respective subscriber device not being added to the at least onefurther information signal.
 10. A radio communication device forreceiving at least one group message transmitted to at least one groupof one or more subscriber devices in at least one radio cell of a radiocommunication network, with a base station of each radio cell beingcontrolled by at least one higher-order radio network controller whichmonitors how many subscriber devices in each radio cell are currentlysubscribed to a respective group, comprising parts for transmitting tothe at least one higher-order radio network controller, via an airinterface of the base station associated with a current location radiocell of the radio communication device, at least one information signalindicating to the at least one higher-order radio controller whether theradio communication device is currently subscribed to the respectivegroup, with a user ID of the radio communication device not being addedto the at least one information signal.
 11. A radio communication deviceas claimed in claim 10, further comprising parts for transmitting to theat least one higher-order radio network controller, via the airinterface of the base station associated with the current location radiocell of the radio communication device, at least one further informationsignal indicating to the at least one higher-order radio networkcontroller whether the radio communication device at least one of can beunsubscribed from the respective group, is leaving the current locationradio cell of the radio communication device, and is switching off, withthe user ID of the radio communication device not being added to the atleast one further information signal.
 12. A radio communication deviceas claimed in claim 10, wherein the radio communication device is amobile communication device.